The present invention relates generally to golf balls and is concerned more particularly with those having a two-piece construction.
The play xe2x80x9cfeelxe2x80x9d and spin rate of a golf ball are particularly important aspects to consider when selecting a golf ball for play. Play xe2x80x9cfeelxe2x80x9d encompasses such subjective and objective attributes as the nature and quality of the club-to-ball contact as transmitted through the club grip to the player and the sound made when the club face impacts the ball. The rate of spin a ball may achieve is of great importance, particularly to the skilled golfer. A golf bail with the capacity to attain a high rate of spin allows the skilled golfer, such as the PGA (Professional Golf Association) professional or low handicap player, the opportunity to maximize control over the golf ball. This is particularly beneficial when hitting a shot on an approach to the green. Thus, golfers of high proficiency generally prefer to play with a ball exhibiting high spin rate capabilities and most typically will select a relatively soft covered ball with which to play.
To attain the objectives of good play feel and high spin rate many skilled golfers traditionally select balata covered balls. The balata covering, whether in the form of a natural or synthetic trans-polyisoprene, creates a ball cover which is relatively soft and typically provides both a good play feel and high spin rate potential. However, balata covered balls suffer from the drawback of low durability. Even in normal use, the softness of the balata covering can easily lead to surface cuts in the covering making the ball unsuitable for further play.
The problems associated with balata covered balls have spurred manufacturers to find other covering materials which are more durable. A particular class of materials used in golf ball covers which has met with success are the ionomer resins. In particular copolymer and terpolymer forms of ionomer resins have been widely used and accepted in golf ball cover materials.
One characteristic of the invention is to provide a golf ball having a soft cover and a soft core.
Another characteristic of the invention is to provide a golf ball having a high potential spin rate which permits the skilled golfer to have a high degree of control over the ball.
Yet another characteristic of the invention is to provide a golf ball having enhanced play feel without sacrificing the distance the ball travels per shot.
An advantage of the invention is to provide a golf ball which produces a pleasing soft sound on impact with a golf club.
Another advantage of the invention is to provide a golf ball with a cover that is as soft, or softer than a balata covered ball, yet is more cut resistant than a balata covered ball.
A final object of the invention is a process for making a golf ball of the type described herein, Other objects, features, advantages and characteristics of the invention will be in part obvious and in part pointed out more in detail hereinafter.
These and other related aspects of the invention are achieved by providing a highly durable golf ball which is relatively xe2x80x9csoftxe2x80x9d. Such a ball comprises a soft core with a cover which in one embodiment has a Shore D hardness of about 57 or less, yielding a ball with a PGA compression of about 62 or less, and in another embodiment, the cover has a Shore D hardness of about 54 or less yielding a ball with a PGA compression of about 67 or less.
In yet another embodiment, the golf ball of the invention has a cover with a Shore D hardness of 57 or less and exhibits a mechanical impedance with a primary minimum value in the range of 2400 Hz or less when maintained at about 21xc2x0 C., 1 atmosphere pressure and 50% relative humidity for at least 15 hours.